10,507 research outputs found
Top Quark Physics at ATLAS: From Cross-Section Measurements to Search for New Particles
No full textThis thesis presents experimental studies of the top quark within the ATLAS experiment at the Large Hadron Collider (LHC). The top quark, with its mass of
172.5 GeV, is the heaviest known elementary particle and possesses unique properties: it has the strongest coupling to the Higgs boson among all SM particles and decays before hadronization, allowing its study as an almost free quark.
Two complementary physics analyses are presented in this thesis. First, the measurement of the single top quark production cross section in the t-channel at a
centre-of-mass energy of √s = 5.02 TeV, using pp collision data corresponding to an integrated luminosity of 255 pb−1 is detailed. After event selections a Boosted
Decision Tree is employed for signal-to-background discrimination, and a Profile Likelihood fit is used to extract the total t-channel cross-section, the individual top-
and antitop-quark production cross-sections, and their ratio. The t-channel single top quark process is observed for the first time at √s = 5.02 TeV with a significance of 6.1σ. The inclusive cross-section for the t-channel single-top production is measured to be σ(tq + ̄tq) = 27.1+4.4 −4.1 (stat.) +4.4 −3.7 (syst.) pb, while the individual cross-sections are measured to be σ(tq) = 19.8+3.9 −3.1 (stat.) +2.9 −2.2 (syst.) pb and σ( ̄tq) = 7.3+3.2 −2.1 (stat.) +2.8 −1.5 (syst.) pb respectively. The ratio between top- and antitop-quark production is found to be Rt = 2.73+1.43 −0.82 (stat.) +1.01 −0.29 (syst.). All measurements are in good agreement with the Standard Model (SM) predictions.
Second, a search for new heavy resonances decaying to top-antitop quark pairs is conducted using the full Run 2 dataset, consisting of 140 fb−1 if pp collisions at √s = 13 TeV. The analysis targets three specific Beyond the Standard Model scenarios: a leptophobic Z′ boson from Top-colour-assisted technicolour, and two variants
of Randall-Sundrum models predicting Kaluza-Klein excitations of the graviton and gluon. The search is performed in the semileptonic decay channel, targeting both re-
solved and boosted topologies, implementing a specialized overlap-removal technique to enhance the sensitivity at high invariant masses. No significant deviation from the SM prediction is observed. Exclusion limits are set on the production cross-section times branching ratio for the considered signal models, obtaining a higher sensitivity in the extracted limits with respect to the previous ATLAS and CMS searches in the same decay channel.
The thesis also includes technical contributions to the ATLAS collaboration combined performance effort, focusing on electron identification in environments with
nearby hadronic jets. This study examines the electron identification process and its efficiencies in challenging scenarios where electron showers overlap with jet constituents. This work contributes to the development of current and especially future physics analyses in the ATLAS collaboration.This thesis presents experimental studies of the top quark within the ATLAS experiment at the Large Hadron Collider (LHC). The top quark, with its mass of
172.5 GeV, is the heaviest known elementary particle and possesses unique properties: it has the strongest coupling to the Higgs boson among all SM particles and decays before hadronization, allowing its study as an almost free quark.
Two complementary physics analyses are presented in this thesis. First, the measurement of the single top quark production cross section in the t-channel at a
centre-of-mass energy of √s = 5.02 TeV, using pp collision data corresponding to an integrated luminosity of 255 pb−1 is detailed. After event selections a Boosted
Decision Tree is employed for signal-to-background discrimination, and a Profile Likelihood fit is used to extract the total t-channel cross-section, the individual top-
and antitop-quark production cross-sections, and their ratio. The t-channel single top quark process is observed for the first time at √s = 5.02 TeV with a significance of 6.1σ. The inclusive cross-section for the t-channel single-top production is measured to be σ(tq + ̄tq) = 27.1+4.4 −4.1 (stat.) +4.4 −3.7 (syst.) pb, while the individual cross-sections are measured to be σ(tq) = 19.8+3.9 −3.1 (stat.) +2.9 −2.2 (syst.) pb and σ( ̄tq) = 7.3+3.2 −2.1 (stat.) +2.8 −1.5 (syst.) pb respectively. The ratio between top- and antitop-quark production is found to be Rt = 2.73+1.43 −0.82 (stat.) +1.01 −0.29 (syst.). All measurements are in good agreement with the Standard Model (SM) predictions.
Second, a search for new heavy resonances decaying to top-antitop quark pairs is conducted using the full Run 2 dataset, consisting of 140 fb−1 if pp collisions at √s = 13 TeV. The analysis targets three specific Beyond the Standard Model scenarios: a leptophobic Z′ boson from Top-colour-assisted technicolour, and two variants
of Randall-Sundrum models predicting Kaluza-Klein excitations of the graviton and gluon. The search is performed in the semileptonic decay channel, targeting both re-
solved and boosted topologies, implementing a specialized overlap-removal technique to enhance the sensitivity at high invariant masses. No significant deviation from the SM prediction is observed. Exclusion limits are set on the production cross-section times branching ratio for the considered signal models, obtaining a higher sensitivity in the extracted limits with respect to the previous ATLAS and CMS searches in the same decay channel.
The thesis also includes technical contributions to the ATLAS collaboration combined performance effort, focusing on electron identification in environments with
nearby hadronic jets. This study examines the electron identification process and its efficiencies in challenging scenarios where electron showers overlap with jet constituents. This work contributes to the development of current and especially future physics analyses in the ATLAS collaboration
First t-channel single top measurement in pp collisions at an energy in the centre-of-mass of √s = 5.02 TeV with the ATLAS experiment
No full textA single top quark production measurement in proton-proton (pp) collisions at the Large Hadron Collider (LHC) at an energy in the centre-of-mass √s = 5.02 TeV with data collected by the ATLAS experiment is reported. This analysis uses a Boosted Decision Tree (BDT) to separate signal from background events and its output distribution is used for a Profile-Likelihood fit. Some of the calibrations used in this analysis are taken from a recent ATLAS top quark pair production cross-section measurement at the same energy of √s = 5.02 TeV (ATLAS Collaboration, JHEP, 06 (2023) 138). The analysis takes into account forward jets to enhance the t-channel process, with an ad-hoc calibration for their energy
First measurement of the t-channel single top production in pp collisions at √s = 5.02$ TeV with the ATLAS experiment
No full textA measurement of single top quark production t−channel cross-section in proton-proton collisions at an energy in the centre-of-mass of √s=5.02 TeV with 257 pb−1 of data collected by the ATLAS experiment at LHC is reported.
This analysis applies event selections to identify t−channel single top candidate events decaying semi-leptonically. Selected events are then used to train a Boosted Decision Tree (BDT) to optimize signal versus background separation. A Profile-Likelihood (PL) fit is performed to measure the total cross-section σ(tq+t ̄q) and the ratio between the top quark (tq), and anti-top quark (t ̄q) cross-sections Rt. The analysis uses forward jets to enhance the t−channel significance (jet η<4.0). Measured values of the cross-section σ(tq+t ̄q)=6.6+4.3−4.0(stat.) +4.4−3.6(syst.) and of the ratio Rt=2.74+1.44−0.83(stat.) +1.04−0.29(syst.) are well in agreement with Standard Model (SM) predictions
Top-quark pair cross-section at √s = 13.6 TeV with the ATLAS experiment
No full textThe ATLAS detector started collecting data in 2022 at the centre-of-mass energy √s = 13.6 TeV. In this report, an analysis of proton-proton collision
data collected in August 2022 by the ATLAS detector at the LHC is shown. The analysis aim is to measure the top-quark pair production cross-section and its ratio to the Z boson production cross-section. Some of the first plots showing a comparison between Run 3 data and predictions in the eμ final state are presented
Measurements of single top quark production processes with the ATLAS and CMS experiments
No full textThis report contains a brief summary of the latest single top quark production cross-section measurements performed by the ATLAS and CMS
collaborations on pp collisions collected during Run 2 of the LHC. Various results for t−channel, s−channel and W associated single top production
are discussed. Particular attention is given to the main techniques used by the analyses and the main systematic uncertainties limiting these precise measurements
Correspondence: Laura Kephart and Arthur Stupka
No full textThis 1936 correspondence, between Laura Kephart (Mrs. Horace Kephart) and Arthur Stupka, concerns a possible Kephart Memorial. Horace Kephart (1862-1931) was a noted naturalist, woodsman, journalist, and author and promoter of the Great Smoky Mountains National Park. Arthur Stupka (1905-1999) was the first park naturalist to work at the Great Smoky Mountains National Park
Mindscapes: Laura Riding's poetry and poetics /
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão.Esta tese propõe uma leitura revisionista da poesia contemporânea através do exame do caso de um dos mais esquecidos escritores norte-americanos do século XX: Laura (Riding) Jackson (1901-1991). O objetivo é demonstrar que Riding não apenas possuía uma poética definida e singular, mas que ela permanece uma das instâncias mais extremas e paradoxais do modernismo anglo-americano, a ponto de Riding abandonar a escrita da poesia em 1938. Recorrendo a conceitos de "formação do cânone" bem como às noções de "discurso" e "função do autor", em Foucault, investigo a construção do cânone da poesia moderna anglo-americana, recuperando o contexto e as circunstâncias da ocultação de Riding. Enquanto cubro os "discursos" poéticos em circulação na primeira metade do século XX-o "imagismo" de Pound, a "dissociação da sensibilidade", "impersonalidade" e "tradição" de Eliot, a "unidade orgância" e "ambigüidade" da Nova Crítica-ofereço um panorama crítico de modernismos alternativos sendo articulados à época. Minha intenção é demonstrar que os poemas de Riding são expressões vigorosas de um escritor para quem "a mente pensando se torna a força ativa do poema", para usar a apta formulação de Charles Bernstein. Entre minhas descobertas sobre as várias e complexas razões que levaram à não-canonização de Riding estão a hegemonia da Nova Crítica, o exílio voluntário de Riding da cena literária (onde são feitas ou desfeitas as reputações), sua recusa em ser antologiada, bem como em ser explicada em termos críticos que não os dela. Todos esses fatores, mais a "dificuldade" de sua poesia, contribuíram para fazer de Riding "a maior poeta esquecida da poesia norte-americana", como escreveu Kenneth Rexroth. Ajudado pelos insights de dois importantes críticos de poesia norte-americana, Charles Bernstein e Marjorie Perloff, defendo que a "poesia da mente" de Riding-onde o que está em jogo é que o que pensamos ser a nossa realidade-representa uma mudança radical no paradigma da poética modernista: de uma poesia centrada na imagem para uma poesia centrada na linguagem. Focalizando a experiência consciente e o tempo duracional do pensamento presente em seus poemas, concluo que as "pensagens" de Riding têm o objetivo preciso de constatar um fato universal: enquanto seres humanos e pensantes, estamos numa condição permanente chamada linguagem
Letter, Julia Gardiner Tyler to Mrs. Laura Holloway, author of First Ladies, dated September 20, 1869
No full textALS of Julia Gardiner Tyler to Mrs. Laura Holloway, author of First Ladies, dated September 20, 1869, about interviewing other first ladies. ALS.Found in:Mss. 65 T97 Additions, Series 1: Mss. Acc. 1993.19 Addition, 186
Heritage tourism: a case study of the Laura Ingalls Wilder Heritage Site at Pepin, Wisconsin
No full textPlan BMany things must be taken into consideration when developing a heritage tourism site. It can be a wonderful opportunity for the community involved to benefit economically and historically. Heritage tourism can keep alive the heritage and traditions of the communities past. When it is discovered that a heritage site exists, the first step is to consult with the community. A site will not succeed without the acceptance and assistance from the community involved. Once the interest is known, the development process can proceed. After determining that there is a heritage tourism site possibility in their area, a commumity must do research to determine the feasibility of the site, what will make it a success, and how to obtain that success. This study will examine a community with a heritage tourism site that has been successful in developing and maintaining it's site. By conducting this study, other communities seeking information for developing their site will have an example and tool to work with. The site chosen for this study is the Laura Ingalls Wilder site in Pepin, Wisconsin. The town is rich with it's heritage associated with Laura Ingalls Wilder. The development and success for this town will be documented through this study. Laura Ingails Wilder is a perfect choice for examining heritage tourism. The author of many American Pioneer books, she has become famous all over the world. In turn all places that she or her family members lived are or are becoming heritage tourism sites. There are older ones that have been in progress for some years, such as the one in Pepin, and there are ones that are being discovered through the popularity of new books written about Laura's family. These communities would benefi greatly from the information this study will produce. Without the bene-fit of this knowledge communities who are unaccustomed to tourism or the way the other Laura Ingalls Wilder sites operate, may make terrible errors in development, tarnishing the site. This may also reflect badly on the other Laura Ingalls Wilder sites. It is important for new Wilder sites to examine all information and know exactly what they are doing when developing the site. If all the Laura Ingalls Wilder sites can benefit from each other's knowledge and experience it will greatly increase the market for all sites. The more detailed and expansive the sites are about their knowledge and sites to see, the more people are going to want to travel to as many sites as possible, learning all they can about the life of Laura Ingalls Wilder and her family. These sites not only attract Laura Ingalls Wilder fans but all people that are interested in the American Pioneer period of the United States history. This study will provide the knowledge for communities who are developing heritage tourism sites, especially those focusing on Laura Ingalls Wilder. This is a very important study for tourism and especially heritage tourism. When a heritage site is discovered communities run into the barrier of not having the experience and knowledge to develop the site properly. This study will analyze tourism in Pepin, Wisconsin to determine it's successfulness due to the fact that it is a Laura Ingalls Wilder heritage tourism site, and Wfit was developed in a way to provide tourists with a view of Laura Ingalls Wilder's past and the past of many Pioneer Americans. By studying this subject it will allow for many people to benefit. Tourist who are seeking the pleasure of the knowledge of the past, and communities who want to preserve their past and profit from tourism
Core Journal Lists: Classic Tool, New Relevance
No full textReviews the historical context of core journal lists, current uses in collection assessment, and existing methodologies for creating lists. Outlines two next generation core list projects developing new methodologies and integrating novel information/data sources to improve precision: a national-level core psychology list and the other a local institutional core list for the interdisciplinary field of urban studies and planning. The paper is based on the authors’ panel presentation at the 2009 ACRL National Conference (Seattle, Washington) titled “Core Journal Lists Re-viewed and Re-imagined.”This is an electronic version of an article published in Robin A. Paynter, Rose M. Jackson & Laura Bowering Mullen (2010): Core Journal Lists: Classic Tool, New Relevance, Behavioral & Social Sciences Librarian, 29:1, 15-31. Behavioral & Social Sciences Librarian is available online at: http://www.tandfonline.com, http://dx.doi.org/10.1080/01639260903571096Peer reviewe
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